• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.428-431
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• 2003

In this paper, distances between elements are optimized for low sidelobe level (SLL) microstrip patch array using Genetic Algorithms. Genetic Algorithms are "global" numerical-optimization methods, it's advantages are very simple coding and fast optimization. This paper show how to optimize the maximum SLL using Genetic Algorithms. In the results, although mutual coupling is neglected, it's maximum SLL is 3.5 dB lower than Uniformly Spaced Array(distance=$0.5{\lambda}$).

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.437-441
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• 2003

The major drawback of the classical microstrip patch antennas Is their narrow band characteristic from 1% to 5%. In this paper, to improve this drawback, we designed the antenna with stacked structure having one drive patch connected with feed line and four identical radiation patches. Resonance is achieved by adjust ing coupling area between one drive patch and four identical radiation patches and changing the size of drive patch or radial ion patches. Used substrate is FR4(${\epsilon}_r$=4.6 and t=1.6mm) and designed center frequency is 2.45GHz. The designed antenna has a wide bandwidth of 380Mhz form 2.333GHz to 2.713GHz(about 15.5%) including ISM band from 2.4GHz to 2.4835GHz.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.256-259
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• 2003

In this paper, a design of multi-layered BPF(bandpass filter) using LTCC(Low Temperature Co-fired Ceramic) process by a lumped-elements is proposed for SOP(system-on-a-chip) of wireless communication systems. The proposed BPF improved a characteristic of rejection band to build an attenuation pole caused by structurally adjacent co-inductance and coupling. The simulation data shows a bandwidth of 90MHz from a center frequency of 2.4GHz, a return loss of 27dB, an insertion loss of 3.2dB, and an attenuation of at least 20dBc at $f_0{\pm}250MHz$. Simulations have used serenade circuit simulation and HFSS EM simulation.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.28-32
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• 2003

Aperture has been employed on the ground plane in the Hair Pin resonator. Aperture made by etching the part of the ground effected coupling coefficient and then quality factor of Hair Pin resonator has been increased. When the hair pin oscillator using aperture has been compared with the conventional hair pin oscillator using microstrip, it has been improved the phase noise about 19dBc @100KHz. Oscillation frequency of the hair pin oscillator using aperture has been 5.83GHz band and output power is -4.33dBm.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.8
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• pp.878-883
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• 2008

In this paper, we propose a double rings structure to improve the balanced-port characteristics of Balun-Bandpass Filter(Balun-BPF). The conventional Balun-BPF has limitations on output symmetry and skirt steepness. We introduce a double rings structure and the suitable coupling point between the two ring resonators to solve these problems. The fabricated double rings Balun-BPF shows excellent characteristics as a Balun-BPF without the conventional limitations.

• Journal of electromagnetic engineering and science
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• v.17 no.4
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• pp.208-220
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• 2017

This paper proposes an experimental optimization method for a wireless power transfer (WPT) system. The power transfer characteristics of a WPT system with arbitrary loads and various types of coupling and compensation networks can be extracted by frequency domain measurements. The various performance parameters of the WPT system, such as input real/imaginary/apparent power, power factor, efficiency, output power and voltage gain, can be accurately extracted in a frequency domain by a single passive measurement. Subsequently, the design parameters can be efficiently tuned by separating the overall design steps into two parts. The extracted performance parameters of the WPT system were validated with time-domain experiments.

• The Transactions of the Korean Institute of Power Electronics
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• v.9 no.1
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• pp.81-87
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• 2004

This paper describes a design method of electromagnetic interference (EMI) filter for pulse-width modulation (PWM) inverter-fed AC drives used for home appliances such as washing machine and air conditioner. The generating and coupling mechanisms of the conducted EMI for AC drives are first investigated. The design procedure of the EMI filter based on the EMI separation principle is then presented. Experiments we carried out for the PWM inverter-fed induction motor drive system and it is shown that the results satisfy the EN55014 EMI regulation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.10a
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• pp.463-468
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• 2011

According to a quantum leap of the performances of automobile, environmental factors are important as functional factors, especially noise. BLDC motor, one of the part of automobile, is also no exception. In this paper, investigation of the sound sources of outer rotor type BLDC motor is performed. In order to reduce noise, it must be necessary knowing sound source. To this end, this paper is analyzed two viewpoints, structural and electromagnetic causes. For structural analysis, modal experiment and 3D mode analysis are performed. On behalf of electromagnetic analysis, 2D finite element method is carried out. Finally, coupling analysis is performed in order to know about influence between two factors.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.684-687
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• 2002

In optical disk drive(ODD), pickup actuator, which comprises a key part of an optical disk drive equipment. must be thin. compact, and high sensitive. Low tilt is also an important requirement for the actuator, since optical disks are to high density. This tilt occurs from around the axis parallel to the tangential and radial direction of the disk. The main reason of the moment is the coupling effect between focus driving system and tracking driving system. This paper analyzed tut quantity due to focusing and tracking force through coupled fields analysts with electromagnetic analysis and structural analysis.

• Journal of electromagnetic engineering and science
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• v.4 no.1
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• pp.8-12
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• 2004

In this paper, a triple-band printed dipole antenna using parasitic elements is proposed for the multiple wireless services. The proposed antenna is designed and experimentally analyzed at the bands of PCS, IMT-2000, and ISM services. To achieve triple frequency operation, the proposed antenna contains two parasitic elements, which act as additional resonators by coupling from the driving dipole antenna. From the measured results, the resonant frequencies of this antenna are 1.79 ㎓, 2.03 ㎓, and 2.41 ㎓ and the measured impedance bandwidths are 90 MHz(1760∼1850 MHz), 210 MHz(1,930∼2,130 MHz), and 30 MHz(2,400∼2,430 MHz) for VSWR<2. The measured antenna gains are 2.14 ㏈i, 0.9 ㏈i, and 0.5 ㏈i, respectively. Antenna parameters for trifle-band operation are investigated and several antenna characteristics are discussed.